NRC TO PROVIDE RESULTS OF INSPECTION INTO SEPT. 15^TH
AUTOMATIC SHUTDOWN OF PEACH BOTTOM NUCLEAR POWER PLANTS
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The meeting, which will be between NRC staff and Exelon management, is scheduled to begin at 6 p.m. at the Peach Bottom Inn, 6085 Delta Road, Delta, Pa. It will be open to the public and there will be at least one opportunity for members of the public to pose questions to NRC staff members before the session is adjourned.

An inspection report detailing the team’s findings will be issued within about 30 days after the meeting.

On September 24, the NRC announced that it was sending an Augmented Inspection Team (AIT) to the plant. The six-member team was tasked with looking at both the causes of, and the plant response to, the automatic reactor shutdowns. An electrical grid disturbance was identified as the initiating cause of the shutdowns.

The event began at about 1:30 a.m. on September 15^th when, at a location far from the plant site, breakers on the grid apparently did not function properly to isolate the effects of a lightning strike. That resulted in a low-voltage condition on both of the off-site power lines that feed Peach Bottom. Like other nuclear power plants, Peach Bottom not only sends power to the grid, it also receives energy back for operational purposes. If those power sources are significantly reduced or interrupted, an affected plant will shut down. That is what automatically occurred at Peach Bottom immediately after its off-site power sources were impacted.

As they are designed to do, the plant’s four emergency diesel generators started upon the interruption of off-site power. Those generators are used to provide power to key safety systems and assist with the safe shutdown of the reactors. At 2:30 a.m., one of the emergency generators tripped, or switched off, because of a problem with its diesel engine coolant system. The plant continued to have sufficient power to safely shut down the reactors. However, following the generator trip, Exelon declared an Unusual Event, based on the shift manager’s discretion, because of what were perceived to be degrading plant conditions. An Unusual Event is the lowest of four levels of emergency classification used by the NRC.

Exelon restored the normal configuration of its power supplies at approximately 7:40 a.m. The Unusual Event was declared over at 10:46 a.m.

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Last revised Wednesday, December 31, 2003